The Relations of the Offensive and Defensive to each other in Tactics

First of all we must inquire into the circumstances which give the victory in a battle.

Of superiority of numbers, and bravery, discipline or other qualities of an army, we say nothing here, because, as a rule, they depend on things which lie out of the province of the art of war in the sense in which we are now considering it; besides which they exercise the same effect in the offensive as the defensive; and, moreover also, the superiority in numbers in general cannot come under consideration here, as the number of troops is likewise a given quantity or condition, and does not depend on the will or pleasure of the general. Further, these things have no particular connection with attack and defence. But, irrespective of these things, there are other three which appear to us of decisive importance, these are: surprise, advantage of ground, and the attack from several quarters. The surprise produces an effect by opposing to the enemy a great many more troops than he expected at some particular point. The superiority in numbers in this case is very different to a general superiority of numbers; it is the most powerful agent in the art of war.

The way in which the advantage of ground contributes to the victory is intelligible enough of itself, and we have only one observation to make, which is, that we do not confine our remarks to obstacles which obstruct the advance of an enemy, such as scarped grounds, high hills, marshy streams, hedges, enclosures, etc.; we also allude to the advantage which ground affords as cover, under which troops are concealed from view. Indeed we may say that even from ground which is apparently featureless a person acquainted with the locality may derive assistance. The attack from several quarters includes in itself all tactical turning movements great and small, and its effects are derived partly from the double execution obtained in this way from firearms, and partly from the enemy’s dread of his retreat being cut off.

Now how do the offensive and defensive stand respectively in relation to these things?

Having in view the three principles of victory just described, the answer to this question is, that only a small portion of the first and last of these principles is in favour of the offensive, whilst the greater part of them, and the whole of the second principle, are at the command of the party acting defensively.

The offensive side can only have the advantage of one complete surprise of the whole mass with the whole, whilst the defensive is in a condition to surprise incessantly, throughout the whole course of the combat, by the force and form which he gives to his partial attacks.

The offensive has greater facilities than the defensive for surrounding and cutting off the whole, as the latter is in a manner in a fixed position while the former is in a state of movement having reference to that position. But the superior advantage for an enveloping movement, which the offensive possesses, as now stated, is again limited to a movement against the whole mass; for during the course of the combat, and with separate divisions of the force, it is easier for the defensive than for the offensive to make attacks from several quarters, because, as we have already said, the former is in a better situation to surprise by the force and form of his attacks.

That the defensive in an especial manner enjoys the assistance which ground affords is plain in itself; as to what concerns the advantage which the defensive has in surprising by the force and form of his attacks, that results from the offensive being obliged to approach by roads and paths where he may be easily observed, whilst the defensive conceals his position, and, until almost the decisive moment, remains invisible to his opponent.
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If the offensive should discover some new and powerful element which it can bring to its assistance -- an event not very probable, seeing the point of simplicity and natural order to which all is now brought -- then the defence must again alter its method. But the defensive is always certain of the assistance of ground, which ensures to it in general its natural superiority, as the special properties of country and ground exercise a greater influence than ever on actual warfare.